Multi-deployment airbag inflator

ABSTRACT

An inflator assembly for an airbag includes a container with a plurality of exhaust ports positioned about a perimeter. A rupturable, non-combustible material covers the perimeter of the container to cover the exhaust ports. A plurality of perforated and rupturable walls define a plurality of chambers concentrically disposed within the container. Within each of the plurality of chambers is a detonator to trigger a gas-producing chemical to inflate an airbag cushion. The detonators disposed in each of the individual chambers can be detonated separately from other detonators in other chambers.

BACKGROUND OF THE INVENTION

[0001] This invention relates to an airbag assembly for a motor vehicle and specifically to an airbag inflator assembly with multiple chambers and detonators. Typically, an airbag assembly includes an airbag cushion and an inflator assembly. Conventional inflator assemblies include a detonator to trigger a gas-producing chemical. Triggering the gas-producing chemical produces a large quantity of rapidly expanding gas that inflates the airbag cushion. The inflator is typically triggered electrically by way of an electronic control module positioned within a motor vehicle. The rapidly expanding gas that inflates the airbag cushion exerts a large force in a relatively short duration of time. This large force is a product of the speed in which an airbag must fully inflate in order to provide impact prevention to occupants of the vehicle during a collision.

[0002] The force of inflation is set at a level such that an occupant of normal size and weight will not be injured. The force of inflation of an airbag cushion required varies depending on the specific size and weight of the occupant. Injury to smaller occupants, such as children is a design consideration taken into account when determining the magnitude of airbag inflation. As appreciated, the large forces exerted by an inflating airbag can cause injury to the occupants they are designed to protect.

[0003] For this reason, warnings and devices are currently in uses that simply turn the air bag off upon the sensing of specific conditions. In some instances a simply switch is installed to turn off the airbag. Other devices sense the size or weight of the occupant and activate the airbag only under a predefined set of conditions. It is well proven that airbag cushions provide an additional level of safety to an occupant during a collision. Devices that disable the airbag remove this level of safety to the detriment of smaller occupants.

[0004] For this reason, it is desirable to develop an airbag assembly that can inflate at various force levels such that the safety benefits of an airbag cushion can be used for occupants of all sizes.

SUMMARY OF THE INVENTION

[0005] An embodiment disclosed in this application is an airbag inflator assembly including multiple chambers each containing separate individually triggerable detonators to control inflation of an airbag cushion.

[0006] The inflator assembly includes a container with a plurality of exhaust ports disposed about a perimeter and covered by a rupturable, non-combustible material. The container is cylindrically shaped and includes a plurality of concentric chambers disposed about a common axis. Each chamber is defined and separated from the other chambers by a perforated and rupturable wall. The walls comprise a structural layer having a plurality of perforations and a non-combustible layer covering the perforations to contain a gas-producing chemical. Each of the chambers includes a detonator for triggering the gas-producing chemical. Each detonator can be triggered separate from any of the others such that the amount of gas discharged to inflate the airbag cushion can be varied and controlled. All detonators can be triggered at once or only predetermined detonators can be triggered to only initiate gas production from specific chambers.

[0007] The disclosed airbag inflator assembly includes multiple chambers, each including an individually triggerable detonator that provides control over the inflation of the airbag cushion to vary the magnitude of force exerted by the airbag cushion during inflation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows:

[0009]FIG. 1 is a cross-sectional view of the air bag inflator;

[0010]FIG. 2 is a cross-sectional view of one chamber of the airbag inflator; and

[0011]FIG. 2A is an enlarged view of the walls dividing the chambers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0012] Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, an inflator assembly for an airbag system is generally indicated at 10 in FIG. 1. The inflator assembly 10 includes a cylindrical container 12 extending between first and second axial ends 14,16. First and second end caps 18 disposed at each of the axial ends 14,16 seal the cylindrical container 12. The container includes chambers 36, 38, and 40 disposed along the axis 42 and defined by perforated and rupturable walls 33.

[0013] Referring to FIGS. 2, a cross-section of one chamber is shown and includes a plurality of exhaust ports 20 extends radially about a perimeter 24 of the cylinder 12 to allow flow of inflating gas emanating from multiple inner chambers. The plurality of exhaust ports 20 comprises at least a minimum flow area for proper gas exhaustion. Further, the number of exhaust ports 20 disposed about the perimeter 24 of the container 12 is of sufficient number to properly vent gas. A worker knowledgeable in the art would understand that the size and number of exhaust ports 20 are dependent on the specific application and would fall within the scope of this invention.

[0014] A rupturable, non-combustible material 22 covers the outer perimeter of the container 12. The rupturable, non-combustible material contains a gas-producing chemical within the container 12. During activation of the detonator to trigger the gas-producing chemical, the rupturable, non-combustible material 22 blows out to allow gas to flow from the container 12 outwardly to inflate an airbag cushion (not shown).

[0015] Referring back to FIG. 1, within the container 12 are a plurality of perforated and rupturable walls 33 defining a plurality of chambers 30,32, and 34. Each of the chambers 30,32, and 34 contains a quantity of gas producing chemical and a detonator 28. Each chamber 30,32, and 34is cylindrical and positioned along a common axis 42

[0016] The detonator 28 in each chamber 36,38, and 40 is preferably triggered by an electric signal initiated from the motor vehicle. Because each chamber 30,32, and 34includes a detonator 28, each chamber 30,32, and 34can detonate independent of any of the other chambers 30,32, and 34. In this manner, inflation of the airbag cushion (not shown) can be initiated by triggering the chambers 30,32, and 34simultaneously, sequentially or individually to control inflation of the airbag cushion.

[0017] Referring to FIG. 2A, the walls 33 defining each individual chamber 30,32, and 34 comprise a multi-layered structure that includes a structural layer 44 to support and define the chamber and a rupturable non-combustible layer 46. The rupturable, non-combustible layer 46 is substantially heat resistance to withstand any heat generated from triggering of the gas-producing chemical. Preferably, the structural layer 44 includes a plurality of exhaust ports 20 communicating with the perforated and rupturable walls 30,32, and 34.

[0018] Referring again to FIG. 2, the each chamber includes a detonation chamber 36 centrally located about the axis 42. A detonator 28 is centrally located within the detonation chamber 36. The wall 30 includes the structural layer 44 and the rupturable layer 46 best shown in FIG. 2A. Disposed about the detonation chamber 36 is the chemical chamber 38 filled with the gas producing chemical 26. Disposed about the chemical chamber 38 is a wall 33 and layer of coarse wire gauze 50. The wire gauze layer 50 is disposed on an inner wall of the chemical chamber 34. The specific configuration of the wire gauze layer 50 is known by those knowledgeable in the art.

[0019] To the outside of the chemical chamber 38 is a concentric space 52 that does not contain the gas producing chemical 26. The next radial layer of the assembly is a perforated and rupturable wall 54. That wall 54 includes the structural layer 44 and the non-combustible material 46. To the outside of the wall 54 is a layer of insulation 56 covered with layers of course and fine wire gauze 58,60. A substantially square shaped bracket 60 surrounds the container 12 to facilitate mounting of the inflator 10 within an airbag assembly.

[0020] The foregoing description is exemplary and not just a material specification. The invention has been described in an illustrative manner, and should be understood that the terminology used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications are within the scope of this invention. It is understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention. 

1. An inflator assembly for an airbag comprising; a container including a plurality of exhaust ports disposed about a perimeter of said container; a rupturable, non-combustible material disposed to covering said exhaust ports; a plurality of perforated and rupturable walls defining a plurality of chambers disposed within said container; a gas-producing chemical disposed within each of said compartments; a detonator disposed in each of said chambers for triggering said gas producing chemical reaction.
 2. The assembly of claim 1, wherein said container is cylindrical and includes end caps to seal axial ends of said cylindrical container.
 3. The assembly of claim 1, wherein each of said compartments within said container are disposed adjacent one another along a common axis.
 4. The assembly of claim 3, wherein said exhaust ports are disposed radially about said container.
 5. The assembly of claim 1, wherein each of said compartments includes a plurality of exhaust ports accessing said perforated and rupturable walls.
 6. The assembly of claim 1, wherein said perforated and rupturable walls are multi-layered.
 7. The assembly of claim 6, wherein said multi-layered perforated and rupturable walls include a structural layer and a substantially non-combustible layer.
 8. The assembly of claim 1, wherein said exhaust ports are sized such that a total flow area through said container is of a minimum orifice size.
 9. The assembly of claim 1, wherein said plurality of exhaust ports is of a number greater than that required to safely exhaust gas produced from said gas producing chemical.
 10. The assembly of claim 1, wherein an electrical signal triggers said detonators.
 11. The assembly of claim 1, wherein said detonators are disposed at fixed lengths relative to each other for isolated unique detonation.
 12. The assembly of claim 1, wherein said assembly is mounted within an external bracket for mounting.
 13. The assembly of claim 1, wherein said perforated and rupturable walls defining a plurality of chambers are disposed parallel with respect to a radial plane.
 14. A method of inflating an airbag comprising the steps of: a. providing an inflator having a plurality of chambers, and each chamber including a gas producing chemical triggered by a detonator; b. actuating at least one of said detonators within said chambers to trigger said gas producing chemical; c. expelling has from said inflator to fill said airbag cushion;
 15. The method of claim 14, wherein said step b. is further defined by detonating a quantity of detonators to provide a predetermined magnitude of force during airbag inflation.
 16. The method of claim 14, wherein said step b. is further defined by actuating said detonators in a predetermined sequential order to control inflation of the airbag cushion.
 17. The method of claim 14, wherein step b is further defined by actuating said detonators to vary a magnitude of force during airbag inflation. 